Evaluating The Efficacy Of Ultrasound-guided Microwave Ablation In Treatment Of Cervical Metastatic Lymph Nodes Of Papillary Thyroid Carcinoma

Objective:Recently,microwave ablation(MWA)has been widely applied to benign and malignant thyroid nodules,with significant outcomes.However,little research exists on the application of MWA for cervical metastatic lymph nodes in papillary thyroid carcinoma(PTC).Moreover,no previous study has compared MWA with reoperation.Therefore,we aimed to evaluate the safety and efficacy of MWA in the treatment of cervical metastatic lymph nodes in PTC by comparing them with those of repeat surgeries.Methods:Between July 2017 and October 2020,67 patients were enrolled in this retrospective study.19 and 48 patients underwent MWA and repeat surgery,respectively.To limit selection bias arising from lack of randomization,1:1 propensity score matching(PSM)was conducted between the two groups by using the nearest-neighbor-matching method,based on the following variables:age at the time of MWA or repeat surgery;sex;number,location,and the largest diameter of MLNs;follow-up time;RAI before MWA or repeat surgery;and interval from diagnosis to treatment.The primary and secondary end-points were recurrence-free survival and complication rates,respectively.The largest diameter,volume and volume reduction ratio(VRR)were analyzed before and after MWA.The effects of different ablation powers on the largest diameter,volume and VRR were investigated.Pre and posttreatment variables(e.g.,baseline characteristics,serum thyroglobulin[Tg]levels,hospitalization time,treatment costs,recurrence-free survival and complication rates)were compared between groups.Results:(1)The largest diameter and volume at the 1-month follow-up were greater than those at preablation,but the differences were not significant(P>0.05).At the last followup,the largest diameter decreased from 1.17±0.08 cm to 0.19±0.07 cm(P<0.001)and the volume reduced from 494.92±775.08 mm~3 to 35.83±143.21 mm~3(P<0.001).The VRR at the last follow-up was 95.57±10.07%.Complete disappearance rates were 5.7%,14.3%,42.9%and 74.3%at the 3-month,6-month,1-year and final follow-ups,respectively.Residual ablation zones were confirmed as having no malignant cells.(2)The power output used was 20 W,25 W and 30 W in our study.During follow-up,the largest diameter and volume gradually decreased but were not significantly different among the three groups(P>0.05).The VRR at the last follow-up was nearly 100%without any significant difference(P>0.05).(3)Compared to reoperation,MWA had a shorter hospitalization time and lower treatment cost(P<0.001).Total and minor complications were higher in the reoperation group(P<0.05),but major complications were comparable(P>0.05).(4)The mean serum Tg levels and biochemical remission rates were not significantly different between the MWA group and reoperation group(P>0.05).(5)In the total cohort,recurrence was not significantly different between the groups(15.8%vs 29.2%,P=0.411).However,the time lag for recurrence was longer in the MWA group(mean time,12 months)than in the reoperation group(mean time,8.57 month).Kaplan-Meier survival curves revealed an insignificant difference in the overall recurrence-free survival rates between the groups(P=0.303).No significant differences existed between the MWA and reoperation groups in the 1-year(89.5%vs 77.1%,P=0.321)and 3-year(84.2%vs 70.8%,P=0.356)recurrence-free survival rates.In the PSM cohort,the recurrence-free survival curves remained similar between the two groups(P=0.401).The 1-year and 3-year recurrence-free survival rates were 94.1%and 88.2%,respectively,for the MWA group and 82.4%and 76.5%,respectively,for the reoperation group.No significant differences existed in the 1-year and 3-year recurrence-free survival rates(P=0.601 and P=0.656,respectively).No distant metastasis occurred during follow-up.Conclusion:Ultrasound-guided MWA for the treatment of cervical metastatic lymph nodes of PTC has the advantages of less trauma,shorter hospitalization time,lower treatment cost,fewer complications,faster postoperative recovery,and aesthetics.It is expected to become an alternative treatment for patients with surgical contraindications and unwillingness to undergo surgical treatment.